1. Field of the Invention
The present invention relates to a coating apparatus and a coating method for applying a resist solution to be coated on the substrate of a semiconductor, liquid crystal, PDP, or printed circuit board, coating solution for an insulating layer or protective layer, or coating solution for a color filter onto a substrate in an optional pattern such as circle, approximate circle, or polygon.
2. Related Art of the Invention
The spin coating method is generally known as a resist-solution coating method used for a fabrication process of a liquid crystal or semiconductor. FIG. 30 shows the theory of the spin coating method. In FIG. 30, symbol 50 denotes a base material, 51 denotes a turntable with a vacuum chuck, 52 denotes a motor and a speed converter, 53 denotes a syringe. First, the base material 50 is fixed onto the turntable 51 with a vacuum chuck to drop a resist solution onto the base material 50 from the syringe 53. Then, by rotating the base material 50 at a high speed (normally, thousands of rpm) by the motor and speed converter 52 connected to the turntable, resist is thinly applied to the surface of the base material due to a centrifugal force. The method disclosed in the official gazette of Japanese Patent Laid-Open No. 224527/1996 is known as another spin coating method.
However, the conventional spin coating method has a problem that, when applying resist onto an approximately-circular wafer almost circularly, most of an expensive resist solution is scattered and thus, the material loss greatly increases. Moreover, a coating thickness becomes irregular depending on the viscosity of a coating solution and this causes a problem on the product quality.
It is an object of the present invention to provide a coating apparatus and a coating method for applying a coating solution to a base material or a substrate in an optional pattern such as a rectangle, square, circle, polygon, or combination of a circle and a polygon, or approximate circle, greatly decreasing the loss of the coating solution, and uniforming the coating thickness.
To achieve the above object, the first invention comprises the running step of running a nozzle and/or a base material, changing step of changing the discharge port slit width of the nozzle, and coating step of discharging a coating solution from the slit and coating the base material with the coating solution, in which the running step, the changing step, and the coating step are executed by combining them. To control a coating thickness to a purposed thickness, the first invention further comprises the supply quantity control step of controlling the supply quantity of the coating solution in accordance with the slit width of the nozzle. Furthermore, it is possible to apply a coating solution at a uniform coating thickness in an optional pattern of a circle or polygon while keeping the pressure in the nozzle and the gap between the base material and the nozzle constant and thereby, substantially decrease the loss of the coating solution to zero.
The second invention comprises blocking means movable in a coating width direction to control the discharge port slit width of a nozzle and driving means obtained by combining a moving unit for moving the blocking means with a controller for controlling the moving distance. The blocking means moves in the nozzle and has a bar interlocking with the blocking means. The bar is present in the manifold of the nozzle and the discharge port slit width is controlled by the lateral of the bar and the blocking plate. When assuming the cross section of the bar in the. direction (X) substantially intersecting the moving direction of the bar as A and the cross section of the internal space of the manifold in the nozzle in the direction (X) as B, an inequality A#B/2 is effected. When the above relation between A and B is satisfied, the problem is solved that a coating solution enters the space in the nozzle formed due to movement of the blocking means to interrupt uniform coating. Therefore, it is possible to apply the coating solution at a uniform thickness in an optional pattern such as a circle or polygon and moreover substantially decrease the loss of the coating solution to zero.
The third invention makes it possible to apply a coating solution to a base material while rotating a nozzle having a discharge port slit gradually widened from the central portion toward the both ends in a coating width direction of the slit and/or a base material about the center of the nozzle in a coating width direction of the nozzle. Therefore, it is possible to uniform the coating thickness on a circular pattern and moreover substantially decrease the loss of a coating solution to zero.
The fourth invention applies a coating solution to a base material while rotating a nozzle having a discharge port slit gradually widened from one end toward the other end in a coating width direction of the slit and/or a base material about the narrowest end of the slit of the nozzle. Therefore, it is possible to uniform the coating thickness on a circular pattern and moreover, substantially decrease the loss of the coating solution.
The fifth invention discharges a coating solution from a slit and moves means for receiving the coating solution provided nearby the discharge port of the slit in a coating width direction. Because a gap is formed between the coating-solution receiving means and the discharge port of the slit, a desired pattern can be applied by removing the coating solution at a portion which should not be coated by the coating-solution receiving means.
The sixth invention discharges a slight amount of coating solution from a slit discharge port immediately before coating, discharges an amount of coating solution corresponding to a predetermined coating thickness from the slit to form a coating film on a base material, and stops the discharge of the coating solution from the slit at the coating end of the base material. The amount of coating solution discharged from the slit discharge port immediately before coating ranges between 0.001 and 1 cc and this amount of coating solution corresponds to an amount of coating solution for filling the gap between the slit discharge port and the base material. Thereby, it is possible to prevent a critical problem that a coating thickness decreases at the coating start end especially at the start of coating or a coating solution contains air and make the coating thickness from the coating start end up to the coating termination end uniform.
As described above, the present invention makes it possible to apply a coating solution onto a substrate with no loss of the coating solution at a uniform coating thickness in an optional pattern and moreover, greatly decrease the cost and improve the product quality in a field of semiconductor or liquid crystal requiring a resist process.